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knocking noise around 2500rpm

 
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killercummins
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Joined: 25 Nov 2009
Posts: 4
Location: Under the hood
296.08 points


1995 Dodge Ram

PostPosted: Thu Apr 01, 2010 10:33 pm    Post subject: knocking noise around 2500rpm Reply with quote

Well i said i would never buy another gas engine but i find myself owning one yet again. To my knowledge and the previous owner its a:

350 marine block
flat top piston unsure about rods and crank
Unsure about cam he is supposed to be bringing me a spec sheet on it but it seems to be around a 290 duration and around .6xx lift. At a
1000rpm idle it pulls 10inch of vacuum
I put all new msd distributor, coil, module and 8.5mm wires with new accel shorty plugs gaped at .050
wieand single plane hi rise intake with a 650 edelbrock off road carb. I had a 750 double pump holley on it but it didn't like steep angles. the previous owner said he ran a 950 demon on it.
Unsure on the heads other than he said they were 2.02 and 1.94 valves with a port job.

I have no idea on the timing settings. i put a timing light on it and set it at 16 btdc bc if i put it any lower it wouldn't run. the distributor didn't come with any mechanical advance springs so i just took it for a test drive after i adjusted the carb for the most vacuum and lowered the idle to 1k. It didn't have any power so i set initial timing to around 20. Same results. So i held it at 3k and adjusted the distributor until it started running smooth. I shut the motor off to see if it would restart easy after it had got warm. I ended up having to back the timing off a little. When i took it down the road i ran great. Then after some off roading i switched form the 750 holley to the edelbrock bc of the flooding on angles.

Now the problem is at around 2500 part throttle with load or no load the engine knocks. it sounds like a bearing knock. It could be the vacuum advance. Im goin to play with that some more tonight. Any thoughts would be appreciated.

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95 dodge ram 2500 2wd 5spd 20mpg country 30 interstate 4k kit, 2095 rack plug, A1 12mm head studs, .020 marine hg, 150hp injectors, full cut delivery valves, no fuel plate, 4'' downpipe 5'' to stack, sbc 3600# 12 button dual disc, II 62/71/14 turbo

Horsepower is how fast you hit the wall, Torque is how far you take the wall with you.
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squeeezer
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Joined: 02 Mar 2007
Posts: 2427
Location: new richmond WI
191524.76 points


1991 Chevrolet Camaro

PostPosted: Fri Apr 02, 2010 12:05 pm    Post subject: Reply with quote

make sure its got the 350 timing cover and balancer
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Big Dave
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Joined: 04 Dec 2005
Posts: 2646
Location: Tampa Florida
119973.02 points



PostPosted: Fri Apr 02, 2010 2:07 pm    Post subject: Reply with quote

Find top dead center and work from there. I would degree that cam to find out what is in there and install a degreed damper with a pointer personally to know what your timing is. Timing it by ear as you are doing invariably results in it being too far advanced.

Big Dave
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af2
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Joined: 01 Sep 2003
Posts: 5558
Location: grassvalley, ca
71227.76 points


1933 Willys Coupe

PostPosted: Fri Apr 02, 2010 8:52 pm    Post subject: Re: knocking noise around 2500rpm Reply with quote

[quote="killercummins"]Well i said i would never buy another gas engine but i find myself owning one yet again. To my knowledge and the previous owner its a:

quote]

The only difference??? You can hear a rod on a gas engine. lol
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killercummins
Newbie


Joined: 25 Nov 2009
Posts: 4
Location: Under the hood
296.08 points


1995 Dodge Ram

PostPosted: Sat Apr 03, 2010 3:53 pm    Post subject: Re: knocking noise around 2500rpm Reply with quote

[quote="af2"]
killercummins wrote:
Well i said i would never buy another gas engine but i find myself owning one yet again. To my knowledge and the previous owner its a:

quote]

The only difference??? You can hear a rod on a gas engine. lol


That seems to be the no. 1 reason most people don't like a diesel bc its loud.

But anyways back to the problem at hand ive played more with the timming and it looks like my little 355 is going to jump to a 383 thanks to scat. I have never seen anybody have very good luck just goin in and replacing bad bearings. Dang if only it was a diesel. Instead of dieing out a 30k with low power and bad mileage. It could have 290k on it pushing 450hp and 900 ft lbs getting 27mpg on interstate.

A little off track but anybody ever seen a diesel hold a flame out the stack thats in the bed of the truck?

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95 dodge ram 2500 2wd 5spd 20mpg country 30 interstate 4k kit, 2095 rack plug, A1 12mm head studs, .020 marine hg, 150hp injectors, full cut delivery valves, no fuel plate, 4'' downpipe 5'' to stack, sbc 3600# 12 button dual disc, II 62/71/14 turbo

Horsepower is how fast you hit the wall, Torque is how far you take the wall with you.
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87IrocTim
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Joined: 10 Jan 2006
Posts: 448

16836.12 points



PostPosted: Tue Apr 06, 2010 4:25 am    Post subject: Reply with quote

nope but ive seen a stripper do some funny things with household utensils. anyways,maybe your extensive gas engine troubles comes from not really being familiar with toying with one? i mean yea diesels are great cuz most of the time from the factory you dont have to go inside it to push big power. fine tuning a performance engine is not an easy task by any means, which is why you may be getting thrown off at the idea...
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"Aerodynamics are for people who can't build engines." -Enzo Ferrari
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